Copper alloy with high strength and high electrical conductivity

ABSTRACT

This copper alloy with high strength and high electrical conductivity includes: Mg: more than 1.0% by mass to less than 4% by mass; and Sn: more than 0.1% by mass to less than 5% by mass, with a remainder including Cu and inevitable impurities, wherein a mass ratio Mg/Sn of a content of Mg to a content of Sn is in a range of 0.4 or more. This copper alloy with high strength and high electrical conductivity may further include Ni: more than 0.1% by mass to less than 7% by mass.

TECHNICAL FIELD

The present invention relates to a copper alloy with high strength andhigh electrical conductivity which is suitable for electronic andelectrical parts such as connectors, lead frames, and the like.

The present application claims priority on Japanese Patent ApplicationNo. 2010-014398 filed on Jan. 26, 2010, and Japanese Patent ApplicationNo. 2010-014399 filed on Jan. 26, 2010, the contents of which areincorporated herein by reference.

BACKGROUND ART

Conventionally, in accordance with a decrease in the sizes of electronicdevices, electrical devices, and the like, efforts have been made todecrease the sizes and the thicknesses of electronic and electricalparts such as connector terminals, lead frames, and the like that areused in the electronic devices, electrical devices, and the like.Therefore, there is a demand for a copper alloy that is excellent inspring properties, strength and electrical conductivity as a materialthat constitutes the electronic and electrical parts.

As a result, as a copper alloy that is excellent in spring properties,strength and electrical conductivity, a Cu—Be alloy containing Be isprovided in, for example, Patent Document 1. This Cu—Be alloy is aprecipitation-hardened alloy with high strength, and the strength isimproved by age-precipitating CuBe in a matrix phase of Cu withoutdegrading the electrical conductivity.

However, the Cu—Be alloy contains an expensive element of Be; andtherefore, the cost of raw materials is extremely high. In addition,when the Cu—Be alloy is manufactured, toxic beryllium oxides aregenerated. As a result, in the manufacturing process, it is necessary toprovide a special configuration of manufacturing facilities and strictlymanage the beryllium oxides in order to prevent the beryllium oxidesfrom being accidentally leaked outside.

As described above, the Cu—Be alloy had problems in that the cost of rawmaterials and the manufacturing cost were both high, and the Cu—Be alloywas extremely expensive. In addition, as described above, since adetrimental element of Be was included, the use of the Cu—Be alloy wasavoided in terms of environmental protection.

As a result, there has been a strong demand for a material that canreplace the Cu—Be alloy.

For example, Non-Patent Document 1 proposes a Cu—Sn—Mg alloy as a copperalloy that replaces the Cu—Be alloy. This Cu—Sn—Mg alloy is produced byadding Mg to a Cu—Sn alloy (bronze), and the Cu—Sn—Mg alloy is an alloythat is excellent in strength and spring properties.

However, the Cu—Sn—Mg alloy described in Non-Patent Document 1 had aproblem in that cracking was liable to occur during working. Since theCu—Sn—Mg alloy described in Non-Patent Document 1 contains a relativelylarge amount of Sn, intermetallic compounds having a low melting pointare unevenly generated in an ingot due to segregation of Sn. When suchintermetallic compounds having a low melting point are generated, theintermetallic compounds having a low melting point remain during asubsequent thermal treatment. As a result, cracking becomes liable tooccur during subsequent working.

In addition, Sn is cheaper than Be; however, Sn is still a relativelyexpensive element. Therefore, the cost of raw materials is increased aswell.

PRIOR ART DOCUMENT Patent Document

-   Patent Document 1: Japanese Unexamined Patent Application, First    Publication No. 04-268033

Non-Patent Document

-   Non-Patent Document 1: P. A. Ainsworth, C. J. Thwaites, R. Duckett,    “Properties and manufacturing characteristics of    precipitation-hardening tin-magnesium bronze,” Metals Technology,    August (1974), p. 385 to 390

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

The present invention has been made in consideration of theabove-described circumstances, and the present invention aims to providea copper alloy with high strength and high electrical conductivity, thecopper alloy does not contain Be; and thereby, the cost of raw materialsand the manufacturing cost are low, and the copper alloy is excellent intensile strength and electrical conductivity, and is also excellent inworkability.

Means for Solving the Problems

A copper alloy with high strength and high electrical conductivityaccording to a first aspect of the present invention includes: Mg: morethan 1.0% by mass to less than 4% by mass; and Sn: more than 0.1% bymass to less than 5% by mass with a remainder including Cu andinevitable impurities, wherein a mass ratio Mg/Sn of a content of Mg toa content of Sn is in a range of 0.4 or more.

The copper alloy with high strength and high electrical conductivityaccording to the first aspect is a copper alloy that contains Mg and Snwith a remainder substantially being Cu and inevitable impurities, andthe content of Mg, the content of Sn, and the range of the mass ratioMg/Sn of the content of Mg to the content of Sn are specified. Thecopper alloy having such a component composition is excellent in tensilestrength, electrical conductivity, and workability as described below.

That is, each of Mg and Sn is an element to improve the strength ofcopper and increase the recrystallization temperature. However, in thecase where large amounts of Mg and Sn are included, the workabilitydeteriorates due to intermetallic compounds including Mg or Sn.Therefore, the content of Mg is set to be in a range of more than 1.0%by mass to less than 4% by mass, and the content of Sn is set to be in arange of more than 0.1% by mass to less than 5% by mass. Thereby, it ispossible to improve the strength and secure the workability.

Furthermore, when both of Mg and Sn are included, precipitates of (Cu,Sn)₂Mg or Cu₄MgSn which are compounds of theses elements are distributedin the matrix phase of copper. Thereby, it is possible to improve thestrength through precipitation hardening. Here, when the mass ratioMg/Sn is set to be in a range of 0.4 or more, the content of Sn does notbecome larger than necessary compared to the content of Mg, and it ispossible to prevent intermetallic compounds having a low melting pointfrom remaining; and thereby, the workability can be secured.

In the copper alloy with high strength and high electrical conductivityaccording to the first aspect, the mass ratio Mg/Sn of the content of Mgto the content of Sn may be in a range of 0.8 to 10.

It is possible to reliably obtain the above-described effect ofimproving the strength due to the including of both of Mg and Sn. Inaddition, the content of Sn is suppressed; and thereby, the workabilitycan be secured.

The copper alloy with high strength and high electrical conductivityaccording to the first aspect may further contain at least one or moreselected from Fe, Co, Al, Ag, Mn, and Zn, and a content thereof may bein a range of 0.01% by mass or more to 5% by mass or less.

Fe, Co, Al, Ag, Mn, and Zn have an effect of improving thecharacteristics of the copper alloy, and it is possible to improve thecharacteristics by selectively including Fe, Co, Al, Ag, Mn, or Zndepending on use.

The copper alloy with high strength and high electrical conductivityaccording to the first aspect may further contain B: 0.001% by mass ormore to 0.5% by mass or less.

B is an element that improves strength and heat resistance. However, inthe case where a large amount of B is included, electrical conductivitydeteriorates. Therefore, the content of B is set to be in a range of0.001% by mass or more to 0.5% by mass or less; and thereby, it ispossible to improve the strength and the heat resistance whilesuppressing degradation of the electrical conductivity.

The copper alloy with high strength and high electrical conductivityaccording to the first aspect may further contain P: less than 0.004% bymass.

P has an effect of lowering the viscosity of a molten copper duringmelting and casting. Therefore, P is frequently added to a copper alloyin order to ease casting operations. However, P reacts with Mg; andthereby, the effect of Mg is reduced. In addition, P is an element thatgreatly degrades the electrical conductivity. Therefore, when thecontent of P is set to be in a range of less than 0.004% by mass, theabove-described effect of Mg is reliably obtained; and thereby, thestrength can be improved. In addition, degradation of the electricalconductivity can be suppressed.

With regard to the copper alloy with high strength and high electricalconductivity according to the first aspect, a tensile strength may be ina range of 750 MPa or more, and an electrical conductivity may be in arange of 10% IACS or more.

In this case, since the strength and the electrical conductivity areexcellent, it is possible to provide a copper alloy with high strengthand high electrical conductivity which is suitable for electronic andelectrical parts. For example, when the copper alloy with high strengthand high electrical conductivity is applied to connector terminals, leadframes, or the like, it is possible to decrease the thickness of theconnector terminals, the lead frames, or the like.

A copper alloy with high strength and high electrical conductivityaccording to a second aspect of the present invention contains Mg: morethan 1.0% by mass to less than 4% by mass, Sn: more than 0.1% by mass toless than 5% by mass, and Ni: more than 0.1% by mass to less than 7% bymass with a remainder including Cu and inevitable impurities, wherein amass ratio Mg/Sn of a content of Mg to a content of Sn is in range of0.4 or more.

The copper alloy with high strength and high electrical conductivityaccording to the second aspect is the copper alloy with high strengthand high electrical conductivity according to the first aspect whichfurther contains Ni at a content of more than 0.1% by mass to less than7% by mass.

The copper alloy with high strength and high electrical conductivityaccording to the second aspect is a copper alloy that contains Mg, Sn,and Ni with a remainder substantially being Cu and inevitableimpurities, and the content of Mg, the content of Sn, the content of Ni,and the range of the mass ratio Mg/Sn of the content of Mg to thecontent of Sn are specified. The copper alloy having such a componentcomposition is excellent in tensile strength, electrical conductivity,and workability as described below.

That is, each of Mg and Sn is an element to improve the strength ofcopper and increase the recrystallization temperature. However, in thecase where large amounts of Mg and Sn are included, the workabilitydeteriorates due to intermetallic compounds including Mg or Sn.Therefore, the content of Mg is set to be in a range of more than 1.0%by mass to less than 4% by mass, and the content of Sn is set to be in arange of more than 0.1% by mass to less than 5% by mass. Thereby, it ispossible to improve the strength and secure the workability.

In detail, when both of Mg and Sn are added, precipitates of (Cu, Sn)₂Mgor Cu₄MgSn are distributed in the matrix phase of copper. The strengthand the recrystallization temperature are improved through precipitationhardening due to the precipitates.

However, in the case where large amounts of Mg and Sn are included,intermetallic compounds containing Mg or Sn are unevenly generated in aningot due to segregation of Mg and Sn. Particularly, intermetalliccompounds including a large amount of Sn have a low melting point; andtherefore, there is a concern that the intermetallic compounds aremelted in a subsequent thermal treatment process. In the case where theintermetallic compounds including a large amount of Sn are melted, theintermetallic compounds become liable to remain in the subsequentthermal treatment. The workability is deteriorated due to the remainingof such intermetallic compounds. Therefore, the content of Mg is set tobe in a range of more than 1.0% by mass to less than 4% by mass, and thecontent of Sn is set to be in a range of more than 0.1% by mass to lessthan 5% by mass.

Furthermore, when the mass Mg/Sn of the content of Mg to the content ofSn is set to be in a range of 0.4 or more, the content of Sn does notbecome larger than necessary compared to the content of Mg, and it ispossible to prevent the generation of intermetallic compounds having alow melting point. Thereby, it is possible to reliably obtain theabove-described effect of improving the strength due to the including ofboth of Mg and Sn. In addition, the workability can be secured.

When Ni is included together with Mg and Sn, Ni has an effect of furtherimproving the strength and the recrystallization temperature. It isassumed that this effect results from precipitates in which Ni issolid-solubilized in (Cu, Sn)₂Mg or Cu₄MgSn. In addition, Ni has aneffect of increasing the melting point of intermetallic compounds whichare generated in an ingot. Therefore, the intermetallic compounds aresuppressed from being melted in a subsequent thermal treatment process;and thereby, it is possible to suppress degradation of the workabilitywhich is caused by the remaining of the intermetallic compounds.Meanwhile, in the case where a large amount of Ni is included, theelectrical conductivity is degraded.

From the above-described circumstances, the content of Ni is set to bein a range of more than 0.1% by mass to less than 7% by mass. Thereby,it is possible to improve the strength, improve the workability, andsecure the electrical conductivity.

In the copper alloy with high strength and high electrical conductivityaccording to the second aspect, a mass ratio Ni/Sn of a content of Ni toa content of Sn may be in a range of 0.2 to 3.

Since the mass ratio Ni/Sn of the content of Ni to the content of Sn isset to be in a range of 0.2 or more, the content of Sn decreases.Therefore, generation of the intermetallic compounds having a lowmelting point can be suppressed; and thereby, the workability can besecured. Furthermore, since the mass ratio Ni/Sn of the content of Ni tothe content of Sn is set to be in a range of 3 or less, an excessiveamount of Ni is not present; and thereby, degradation of the electricalconductivity can be prevented.

The copper alloy with high strength and high electrical conductivityaccording to the second aspect may further contain either one or both ofP and B, and a content thereof may be in a range of 0.001% by mass ormore to 0.5% by mass or less.

P and B are elements that improve strength and heat resistance. Inaddition, P has an effect of lowering the viscosity of molten copperduring melting and casting. However, in the case where large amounts ofP and B are included, the electrical conductivity is degraded.Therefore, when the contents of P and B are set to be in a range of0.001% by mass to 0.5% by mass, the strength and the heat resistance canbe improved while suppressing degradation of the electricalconductivity.

The copper alloy with high strength and high electrical conductivityaccording to the second aspect may further contain at least one or moreselected from Fe, Co, Al, Ag, Mn, and Zn, and a content thereof may bein a range of 0.01% by mass or more to 5% by mass or less.

Fe, Co, Al, Ag, Mn, and Zn have an effect of improving thecharacteristics of the copper alloy, and it is possible to improve thecharacteristics by selectively including one or more of Fe, Co, Al, Ag,Mn, and Zn depending on use.

With regard to the copper alloy with high strength and high electricalconductivity according to the second aspect, a tensile strength may bein a range of 750 MPa or more, and an electrical conductivity may be ina range of 10% IACS or more.

In this case, since the strength and the electrical conductivity areexcellent, it is possible to provide a copper alloy with high strengthand high electrical conductivity which is suitable for electronic andelectrical parts. For example, when the copper alloy with high strengthand high electrical conductivity is applied to connector terminals, leadframes, or the like, it is possible to decrease the thickness of theconnector terminals, the lead frames, or the like.

Effects of the Invention

According to the first and second aspects of the invention, it ispossible to provide a copper alloy with high strength and highelectrical conductivity, and the copper alloy does not contain Be; andtherefore, the raw material cost and the manufacturing cost are low. Inaddition, the copper alloy is excellent in tensile strength andelectrical conductivity, and is also excellent in workability.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, a copper alloy with high strength and high electricalconductivity according to an embodiment of the present invention will bedescribed.

First Embodiment

A copper alloy with high strength and high electrical conductivityaccording to a first embodiment has a composition which includes: Mg:more than 1.0% by mass to less than 4% by mass; Sn: more than 0.1% bymass to less than 5% by mass; at least one or more selected from Fe, Co,Al, Ag, Mn, and Zn: 0.01% by mass or more to 5% by mass or less; B:0.001% by mass or more to 0.5% by mass or less; and P: less than 0.004%by mass with a remainder being Cu and inevitable impurities.

In addition, the mass ratio Mg/Sn of the content of Mg to the content ofSn is in a range of 0.4 or more.

In the copper alloy with high strength and high electrical conductivityaccording to the first embodiment, the tensile strength is in a range of750 MPa or more, and the electrical conductivity is in a range of 10%IACS or more.

Hereinafter, reasons why the contents of the above elements are limitedin the above ranges will be described.

(Mg)

Mg is an element having an effect of improving the strength withoutgreatly degrading the electrical conductivity. In addition, Mg has aneffect of increasing the recrystallization temperature. Here, in thecase where the content of Mg is in a range of 1.0% by mass or less, theabove-described effects cannot be obtained.

On the other hand, in the case where the content of Mg is in a range of4.0% by mass or more, intermetallic compounds including Mg remain when athermal treatment is carried out for homogenization and solutiontreatment. Thereby, sufficient homogenization and solution treatmentcannot be carried out. As a result, there is a concern that cracking mayoccur in cold working or hot working after the thermal treatment.

From such reasons, the content of Mg is set to be in a range of morethan 1.0% by mass to less than 4% by mass.

Furthermore, Mg is a reactive metal. Therefore, in the case where anexcessive amount of Mg is added, there is a concern that Mg oxidesgenerated by reactions with oxygen may be included during melting andcasting. In order to suppress the including of the Mg oxides, thecontent of Mg is preferably set to be in a range of more than 1.0% bymass to less than 3% by mass.

(Sn)

Sn is an element of being solid-solubilized in a matrix phase of copper;and thereby, Sn has an effect of improving the strength and increasingthe recrystallization temperature. Here, in the case where the contentof Sn is in a range of 0.1% by mass or less, the effects cannot beobtained.

On the other hand, in the case where the content of Sn is in a range of5% by mass or more, the electrical conductivity is greatly decreased. Inaddition, intermetallic compounds containing Sn and having a low meltingpoint are unevenly generated due to segregation of Sn. Therefore, theintermetallic compounds containing Sn and having a low melting pointremain when a thermal treatment is carried out for homogenization andsolution treatment. Thereby, sufficient homogenization and solutiontreatment cannot be carried out. As a result, there is a concern thatcracking may occur in cold working or hot working after the thermaltreatment. In addition, Sn is a relatively expensive element. Therefore,in the case in where Sn is added at a content of more than necessary,the manufacturing cost increase.

From such reasons, the content of Sn is set to be in range of more than0.1% by mass to less than 5% by mass. Meanwhile, in order to reliablyobtain the above-described effects, the content of Sn is preferably setto be in a range of more than 0.1% by mass to less than 2% by mass.

(Mg/Sn)

In the case where both of Mg and Sn are included, precipitates of (Cu,Sn)₂Mg or Cu₄MgSn, which are compounds thereof, are distributed in thematrix phase of copper; and thereby, the strength can be improved due toprecipitation hardening.

Here, in the case where the mass ratio Mg/Sn of the content of Mg to thecontent of Sn is in a range of less than 0.4, a large amount of Sn isincluded compared to the content of Mg. In this case, as describedabove, the intermetallic compounds having a low melting point becomeliable to be generated; and thereby, the workability is degraded.

From such reasons, the mass ratio Mg/Sn of the content of Mg to thecontent of Sn is set to be in a range of 0.4 or more; and thereby, theworkability is secured.

Meanwhile, in order to suppress the remaining of the intermetalliccompounds containing Sn and having a low melting point so as to reliablysecure the workability and to reliably obtain the effect of improvingthe strength due to Sn, the mass ratio Mg/Sn of the content of Mg to thecontent of Sn is preferably set to be in a range of 0.8 to 10.

(Fe, Co, Al, Ag, Mn, and Zn)

Fe, Co, Al, Ag, Mn, and Zn have an effect of improving thecharacteristics of a copper alloy, and it is possible to improve thecharacteristics by selectively including one or more of Fe, Co, Al, Ag,Mn, and Zn in accordance with use. Here, in the case where the contentof at least one or more of elements selected from Fe, Co, Al, Ag, Mn,and Zn is in a range of less than 0.01% by mass, the effects cannot beobtained.

On the other hand, in the case where the content of at least one or moreof elements selected from Fe, Co, Al, Ag, Mn, and Zn exceeds 5% by mass,the electrical conductivity is greatly degraded.

From such reasons, the content of at least one or more of elementsselected from Fe, Co, Al, Ag, Mn, and Zn is set to be in a range of0.01% by mass to 5% by mass.

(B)

B is an element that improves the strength and the heat resistance.Here, in the case where the content of B is in a range of less than0.001% by mass, the effects cannot be obtained.

On the other hand, in the case where the content of B exceeds 0.5% bymass, the electrical conductivity is greatly degraded.

From such reasons, the content of B is set to be in a range of 0.001% bymass or more to 0.5% by mass or less.

(P)

P has an effect of lowering the viscosity of molten copper duringmelting and casting. Therefore, P is frequently added to a copper alloyin order to ease casting operations. However, since P reacts with Mg, Preduces the effect of Mg. In addition, P is an element that greatlydegrades the electrical conductivity.

Therefore, in order to reliably obtain the effects of Mg and to suppressdegradation of the electrical conductivity, the content of P is set tobe in a range of less than 0.004% by mass.

Meanwhile, the inevitable impurities include Ca, Sr, Ba, Sc, Y, rareearth elements, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Re, Ru, Os, Se, Te, Rh,Ir, Pd, Pt, Au, Cd, Ga, In, Li, Si, Ge, As, Sb, Ti, Tl, Pb, Bi, S, O, C,Be, N, H, Hg, and the like. The inevitable impurities are preferablyincluded at a total content of 0.3% by mass or less.

With regard to the copper alloy with high strength and high electricalconductivity according to the first embodiment having theabove-described chemical components, Mg and Sn are included, the contentof Mg is set to be in a range of more than 1.0% by mass to less than 4%by mass, the content of Sn is set to be in a range of more than 0.1% bymass to less than 5% by mass, and the mass ratio Mg/Sn of the content ofMg to the content of Sn is set to be in a range of 0.4 or more.Therefore, by including both of Mg and Sn, it is possible to improve thestrength due to solid solution hardening and precipitation hardening. Inaddition, and the contents of Mg and Sn are suppressed; and thereby, theworkability can be secured.

In addition, at least one or more selected from Fe, Co, Al, Ag, Mn, andZn are included, and the content thereof is set to be in a range of0.01% by mass or more to 5% by mass or less. Therefore, due to one ormore elements selected from Fe, Co, Al, Ag, Mn, and Zn, it is possibleto improve the characteristics of the copper alloy without greatlydegrading the electrical conductivity.

Furthermore, B is included, and the content thereof is set to be in arange of 0.001% by mass or more to 0.5% by mass or less. Therefore, itis possible to improve the strength and the heat resistance whilesuppressing degradation of the electrical conductivity.

In addition, since the content of P is set to be in a range of less than0.004% by mass, it is possible to suppress a reaction between Mg and P;and thereby, the effects of Mg can be reliably obtained.

Furthermore, in the first embodiment, the tensile strength is in a rangeof 750 MPa or more, and the electrical conductivity is in a range of 10%IACS or more. Therefore, when the copper alloy with high strength andhigh electrical conductivity according to the first embodiment isapplied to connector terminals, lead frames, or the like, it is possibleto decrease the thickness of the connector terminals, the lead frames,or the like.

Second Embodiment

A copper alloy with high strength and high electrical conductivityaccording to a second embodiment has a composition which includes: Mg:more than 1.0% by mass to less than 4% by mass, Sn: more than 0.1% bymass to less than 5% by mass, Ni: more than 0.1% by mass to less than 7%by mass, either one or both of P and B: 0.001% by mass or more to 0.5%by mass or less, at least one or more selected from Fe, Co, Al, Ag, Mn,and Zn: 0.01% by mass or more to 5% by mass or less with a remainderbeing Cu and inevitable impurities.

In addition, the mass ratio Mg/Sn of the content of Mg to the content ofSn is in a range of 0.4 or more, and the mass ratio Ni/Sn of the contentof Ni to the content of Sn is in a range of 0.2 to 3.

The second embodiment is different from the first embodiment in that Niis further included and the content of P is in a range of 0.001% by massor more to 0.5% by mass or less in the second embodiment.

Hereinafter, reasons why the contents of the above elements are limitedin the above ranges will be described.

(Mg)

Mg is an element having an effect of improving the strength withoutgreatly degrading the electrical conductivity. In addition, Mg has aneffect of increasing the recrystallization temperature. Here, in thecase where the content of Mg is in a range of 1.0% by mass or less, theabove-described effects cannot be obtained.

On the other hand, in the case where the content of Mg is in a range of4.0% by mass or more, intermetallic compounds including Mg remain when athermal treatment is carried out for homogenization and solutiontreatment. Thereby, sufficient homogenization and solution treatmentcannot be carried out. As a result, there is a concern that cracking mayoccur in cold working or hot working after the thermal treatment.

From such reasons, the content of Mg is set to be in a range of morethan 1.0% by mass to less than 4% by mass.

Furthermore, Mg is a reactive metal. Therefore, in the case where anexcessive amount of Mg is added, there is a concern that Mg oxidesgenerated by reactions with oxygen may be included during melting andcasting. In order to suppress the including of the Mg oxides, thecontent of Mg is preferably set to be in a range of more than 1.0% bymass to less than 3% by mass.

(Sn)

Sn is an element of being solid-solubilized in a matrix phase of copper;and thereby, Sn has an effect of improving the strength and increasingthe recrystallization temperature. Here, in the case where the contentof Sn is in a range of 0.1% by mass or less, the effects cannot beobtained.

On the other hand, in the case where the content of Sn is in a range of5% by mass or more, the electrical conductivity is greatly decreased. Inaddition, intermetallic compounds containing Sn and having a low meltingpoint are unevenly generated due to segregation of Sn. Therefore, theintermetallic compounds containing Sn and having a low melting pointremain when a thermal treatment is carried out for homogenization andsolution treatment. Thereby, sufficient homogenization and solutiontreatment cannot be carried out. As a result, there is a concern thatcracking may occur in cold working or hot working after the thermaltreatment. In addition, Sn is a relatively expensive element. Therefore,in the case in where Sn is added at a content of more than necessary,the manufacturing cost increase.

From such reasons, the content of Sn is set to be in range of more than0.1% by mass to less than 5% by mass. Meanwhile, in order to reliablyobtain the above-described effects, the content of Sn is preferably setto be in a range of more than 0.1% by mass to less than 2% by mass.

(Ni)

Ni is an element having effects of improving the strength and increasingthe recrystallization temperature when Ni is included together with Mgand Sn. In addition, Ni has an effect of increasing a melting point ofintermetallic compounds that segregate in an ingot. Therefore, meltingof the intermetallic compounds in a subsequent thermal treatment can besuppressed; and thereby, an effect of improving the workability isobtained. Here, in the case where the content of Ni is in a range of0.1% by mass or less, the effects cannot be obtained.

On the other hand, in the case where the content of Ni is in a range of7% by mass or more, the electrical conductivity becomes greatlydegraded.

From such reasons, the content of Ni is set to be in a range of morethan 0.1% by mass to less than 7% by mass.

(Mg/Sn)

In the case where both of Mg and Sn are included, precipitates of (Cu,Sn)₂Mg or Cu₄MgSn, which are compounds thereof, are distributed in thematrix phase of copper; and thereby, the strength can be improved due toprecipitation hardening.

Here, in the case where the mass ratio Mg/Sn of the content of Mg to thecontent of Sn is in a range of less than 0.4, a large amount of Sn isincluded compared to the content of Mg. In this case, as describedabove, the intermetallic compounds having a low melting point aregenerated; and thereby, the workability is degraded.

Therefore, the mass ratio Mg/Sn of the content of Mg to the content ofSn is set to be in a range of 0.4 or more; and thereby, the workabilityis secured.

Meanwhile, in order to suppress the remaining of the intermetalliccompounds containing Sn and having a low melting point so as to reliablysecure the workability and to reliably obtain the effect of improvingthe strength due to Sn, the mass ratio Mg/Sn of the content of Mg to thecontent of Sn is preferably set to be in a range of 0.8 to 10.

(Ni/Sn)

In the case where the mass ratio Ni/Sn of the content of Ni to thecontent of Sn is in a range of less than 0.2, a large amount of Sn isincluded compared to the content of Ni. In this case, as describedabove, intermetallic compounds having a low melting point become liableto be generated; and thereby, the workability is degraded.

In addition, in the case where the mass ratio Ni/Sn of the content of Nito the content of Sn exceeds 3, the content of Ni increases; andthereby, the electrical conductivity greatly degrades.

Therefore, the mass ratio Ni/Sn of the content of Ni to the content ofSn is set to be in a range of 0.2 to 3; and thereby, the workability issecured while securing the electrical conductivity.

(B, P)

B and P are elements that improve the strength and the heat resistance.In addition, P has an effect of lowering the viscosity of molten copperduring melting and casting. Here, in the case where the contents of Band P are in a range of less than 0.001% by mass, the effects cannot beobtained.

On the other hand, in the case where the contents of B and P exceed 0.5%by mass, the electrical conductivity greatly degrades.

From such reasons, the contents of either one or both of B and P are setto be in a range of 0.001% by mass or more to 0.5% by mass or less.

(Fe, Co, Al, Ag, Mn, and Zn)

Fe, Co, Al, Ag, Mn, and Zn have an effect of improving thecharacteristics of a copper alloy, and it is possible to improve thecharacteristics by selectively including one or more of Fe, Co, Al, Ag,Mn, and Zn in accordance with use. Here, in the case where the contentof at least one or more of elements selected from Fe, Co, Al, Ag, Mn,and Zn is in a range of less than 0.01% by mass, the effects cannot beobtained.

On the other hand, in the case where the content of at least one or moreof elements selected from Fe, Co, Al, Ag, Mn, and Zn exceeds 5% by mass,the electrical conductivity is greatly degraded.

From such reasons, the content of at least one or more of elementsselected from Fe, Co, Al, Ag, Mn, and Zn is set to be in a range of0.01% by mass to 5% by mass.

Meanwhile, the inevitable impurities include Ca, Sr, Ba, Sc, Y, rareearth elements, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Re, Ru, Os, Se, Te, Rh,Ir, Pd, Pt, Au, Cd, Ga, In, Li, Si, Ge, As, Sb, Ti, Tl, Pb, Bi, S, O, C,Be, N, H, Hg, and the like. The inevitable impurities are preferablyincluded at a total content of 0.3% by mass or less.

With regard to the copper alloy with high strength and high electricalconductivity according to the second embodiment having theabove-described chemical components, Mg, Sn, and Ni are included, thecontent of Mg is set to be in a range of more than 1.0% by mass to lessthan 4% by mass, the content of Sn is set to be in a range of more than0.1% by mass to less than 5% by mass, and the content of Ni is set to bein a range of more than 0.1% by mass to less than 7% by mass. Therefore,by including all of Mg, Sn, and Ni it is possible to improve thestrength due to solid solution hardening and precipitation hardening. Inaddition, the contents of Mg, Sn, and Ni are suppressed; and thereby,the workability and the electrical conductivity can be secured.

In addition, either one or both of P and B are included, and thecontents are set to be in a range of 0.001% by mass or more to 0.5% bymass or less. Therefore, it is possible to improve the strength and theheat resistance while suppressing degradation of the electricalconductivity.

Furthermore, at least one or more selected from Fe, Co, Al, Ag, Mn, andZn are included, and the content is set to be in a range of 0.01% bymass or more to 5% by mass or less. Therefore, due to one or moreelements selected from Fe, Co, Al, Ag, Mn, and Zn, it is possible toimprove the characteristics of the copper alloy without greatlydegrading the electrical conductivity.

Furthermore, in the second embodiment, the tensile strength is in arange of 750 MPa or more, and the electrical conductivity is in a rangeof 10% IACS or more. Therefore, when the copper alloy with high strengthand high electrical conductivity according to the second embodiment isapplied to connector terminals, lead frames, or the like, it is possibleto decrease the thickness of the connector terminals, the lead frames,or the like.

(Method of Manufacturing the Copper Alloy with High Strength and HighElectrical Conductivity)

Next, a method for manufacturing the copper alloys with high strengthand high electrical conductivity according to the first and secondembodiments will be described.

(Melting and Casting Process)

Firstly, copper raw materials are melted to obtain molten copper, andthe above-described components are added to the obtained molten copperso as to conduct component adjustment. Thereby, a molten copper alloy isproduced. Meanwhile, a single element, a master alloy, or the like canbe used as the raw materials including the elements that are added. Inaddition, the raw materials including the elements may be meltedtogether with the copper raw materials. In addition, recycled materialsand scrap materials of the present alloy may also be used.

Here, the molten copper is preferably 4NCu having a purity of 99.99% ormore. In addition, in the melting process, a vacuum furnace or anatmosphere furnace of which atmosphere is an inert gas atmosphere or areduction atmosphere is preferably used in order to suppress oxidizationof Mg and the like.

Then, the molten copper alloy of which the components are adjusted iscasted into a mold so as to produce ingots. Meanwhile, in the case wheremass production is taken into account, it is preferable to apply acontinuous casting method or a semi-continuous casting method.

(First Thermal Treatment Process)

Next, a first thermal treatment process is carried out forhomogenization and solution treatment of the obtained ingots. During theprogress of solidification, the added elements segregate andconcentrate; and thereby, intermetallic compounds and the like aregenerated. In the interior of the ingot, these intermetallic compoundsand the like are present. Therefore, the ingots are subjected to thefirst thermal treatment; and thereby, the added elements are evenlydispersed, and the added elements are solid-solubilized in the matrixphase of the copper in the ingots. As a result, segregation of theintermetallic compounds and the like is eliminated or reduced, or theintermetallic compounds are eliminated or reduced.

Conditions for the thermal treatment in the first thermal treatmentprocess are not particularly limited; however, it is preferable that thefirst thermal treatment is carried out at a temperature of 500° C. to800° C. in a non-oxidation atmosphere or a reduction atmosphere.

In addition, hot working (hot processing) may be carried out after theabove-described first thermal treatment in order to increase theefficiency of rough processing and the uniformity of the structure. Theworking method is not particularly limited; for example, rolling can beemployed in the case where the final form is a sheet or a strip. Wiredrawing, extrusion, groove rolling, and the like can be employed in thecase where the final form is a line or a rod. In addition, forging orpressing can be employed in the case where the final form is a bulkshape. Meanwhile, the temperature of the hot working is also notparticularly limited; however, it is preferable that the temperature ofthe hot working is set to be in a range of 500° C. to 800° C.

(Working Process)

The heat-treated ingots are cut, and surface milling is carried out inorder to remove oxidized films and the like that are generated by thethermal treatment and the like. Then, working (processing) is carriedout in order to have a predetermined shape.

Here, a working method is not particularly limited; for example, rollingcan be employed in the case where the final form is a sheet or a strip.Wire drawing, extrusion, groove rolling, and the like can be employed inthe case where the final form is a line or a rod. In addition, forgingor pressing can be employed in the case where the final form is a bulkshape. Meanwhile, the temperature conditions of the working are notparticularly limited; however, the working is preferably cold working orwarm working. In addition, the working rate is appropriately adjusted soas to have a shape approximate to the final shape; however, the workingrate is preferably in a range of 20% or more.

Meanwhile, during the working process, a thermal treatment may beappropriately carried out in order to promote solution treatment, toobtain recrystallized structures, or to improve the workability.Conditions for the thermal treatment are not particularly limited;however, it is preferable that the thermal treatment is carried out at atemperature of 500° C. to 800° C. in a non-oxidation atmosphere or areduction atmosphere.

(Second Thermal Treatment Process)

Next, the processed materials obtained through the working process issubjected to a second thermal treatment in order to carry out hardeningdue to low-temperature annealing and precipitation hardening, or toremove residual strains. Conditions of the second thermal treatment areappropriately set depending on characteristics that are required forproducts to be produced.

Meanwhile, the conditions of the second thermal treatment are notparticularly limited; however, it is preferable that the second thermaltreatment is carried out at a temperature of 150° C. to 600° C. for 10seconds to 24 hours in a non-oxidation atmosphere or a reductionatmosphere. In addition, the working prior to the second thermaltreatment and the second thermal treatment may be carried out aplurality of times.

In accordance with the above-described manner, the copper alloys withhigh strength and high electrical conductivity of the first and secondembodiments are produced (manufactured).

The copper alloys with high strength and high electrical conductivity ofthe embodiments of the present invention are explained. The presentinvention is not limited thereto, and the embodiments can beappropriately modified within the scope of the technical features of thepresent invention.

For example, the first embodiment is explained that the copper alloycontains elements other than Mg and Sn; however, the present inventionis not limited thereto, and elements other than Mg and Sn may be addedaccording to necessity.

The second embodiment is explained that the copper alloy containselements other than Mg, Sn, and Ni; however, the present invention isnot limited thereto, and elements other than Mg, Sn, and Ni may be addedaccording to necessity.

In addition, an example of the method for manufacturing the copperalloys with high strength and high electrical conductivity according tothe first and second embodiments is explained; however, themanufacturing method is not limited to the embodiment, and existingmanufacturing methods may be appropriately selected so as to manufacturethe copper alloys.

EXAMPLES

Hereinafter, the results of confirmation tests that were carried out toconfirm the effects of the embodiments will be described.

A copper raw material composed of oxygen-free copper having a purity of99.99% or more was prepared. The copper raw material was fed into ahighly pure graphite crucible, and the copper raw material was meltedusing a high frequency heater in an atmosphere furnace having an Ar gasatmosphere. A variety of elements were added to the obtained moltencopper so as to prepare the component compositions shown in Table 1.Next, molten copper alloys were casted into carbon casting molds so asto produce ingots. Meanwhile, the sizes of the ingot were set to athickness of approximately 20 mm×a width of approximately 20 mm×a lengthof approximately 100 mm.

The obtained ingots were subjected to a thermal treatment (a firstthermal treatment) at 715° C. for 4 hours in an Ar gas atmosphere.

The heat-treated ingots were cut, and surface milling was carried out inorder to remove oxidation films. Thereby, body blocks having a thicknessof approximately 8 mm×a width of approximately 18 mm×a length ofapproximately 100 mm were produced.

The body blocks were subjected to cold rolling at a rolling reduction ofapproximately 92% to 94% so as to produce strips having a thickness ofapproximately 0.5 mm×a width of approximately 20 mm.

Each of the strips was subjected to a thermal treatment (a secondthermal treatment) at a temperature as described in Table 1 for 1 hourto 4 hours in an Ar gas atmosphere so as to manufacture a strip forcharacteristics evaluation.

(Workability Evaluation)

Presence or absence of cracked edges during the above-described coldrolling was observed to evaluate the workability. Copper alloys in whichno or little cracked edges were visually observed were evaluated to be A(excellent), copper alloys in which small cracked edges having a lengthof less than 1 mm were caused were evaluated to be B (good), copperalloys in which cracked edges having a length of 1 mm to less than 3 mmwere caused were evaluated to be C (fair), copper alloys in which largecracked edges having a length of 3 mm or more were caused were evaluatedto be D (bad), and copper alloys which were broken due to cracked edgesduring the rolling were evaluated to be E (very bad).

Meanwhile, the length of the cracked edge refers to the length of thecracked edge from the end portion in the width direction toward thecenter portion in the width direction of the rolled material.

In addition, the tensile strengths and the electrical conductivities ofthe strips for characteristics evaluation were measured by the followingmethod.

(Tensile Strength)

Test specimens No. 13B defined by JIS Z 2201 were taken from the stripsfor characteristics evaluation, and the tensile strengths of the testspecimens were measured at room temperature (25° C.) according to theregulations of JIS Z 2241. Meanwhile, the test specimens were taken in astate in which the tensile direction in the tensile tests was inparallel with the rolling direction of the strips for characteristicsevaluation.

(Electrical Conductivity)

Test specimens having a width of 10 mm×a length of 60 mm were taken fromthe strips for characteristics evaluation, and electrical resistance wasobtained by the four-terminal method. In addition, dimensions of thetest specimens were measured using a micrometer, and volumes of the testspecimens were calculated. Then, electrical conductivities werecalculated from the measured electrical resistance values and the valuesof the volumes. Meanwhile, the test specimens were taken in a state inwhich the longitudinal direction of the test specimens was in parallelwith the rolling direction of the strips for characteristics evaluation.

The evaluation results are shown in Tables 1 to 3.

TABLE 1 Thermal Electrical Mg Sn Others treatment conditions Tensileconductivity No. (mass %) (mass %) Mg/Sn (mass %) Cracked edgeTemperature Time strength (MPa) (% IACS) Invention 1-1  1.17 0.19 6.16 —A 200° C. 1 h 752 44 example 1-2  1.16 0.95 1.22 — A 200° C. 1 h 774 351-3  1.16 1.88 0.62 — A 300° C. 2 h 787 31 1-4  1.15 2.81 0.41 — B 300°C. 2 h 803 25 1-5  1.77 0.19 9.32 — A 200° C. 1 h 803 37 1-6  1.76 0.961.83 — A 300° C. 1 h 821 33 1-7  1.75 1.90 0.92 — B 300° C. 4 h 897 321-8  1.75 2.84 0.62 — B 300° C. 2 h 962 28 1-9  2.01 4.53 0.44 — B 200°C. 1 h 890 15 1-10 2.38 0.19 12.53 — B 200° C. 1 h 864 31 1-11 2.37 0.972.44 — B 300° C. 4 h 965 32 1-12 2.37 1.44 1.65 — B 300° C. 4 h 942 321-13 3.22 0.20 16.10 — C 200° C. 1 h 924 28 1-14 3.64 0.20 18.20 — C200° C. 1 h 929 27 1-15 1.77 0.19 9.32 P: 0.003 B 200° C. 1 h 804 361-16 1.77 0.19 9.32 B: 0.02 B 200° C. 1 h 814 36 1-17 1.77 0.19 9.32 Fe:0.09 B 200° C. 1 h 814 31 1-18 1.77 0.19 9.32 Co: 0.10 B 200° C. 1 h 82032 1-19 1.77 0.20 9.23 Al: 1.78 B 200° C. 1 h 871 19 1-20 1.77 0.19 9.32Ag: 0.17 B 200° C. 1 h 832 37 1-21 1.77 0.19 9.32 Mn: 2.68 B 200° C. 1 h837 13 1-22 1.77 0.19 9.32 Zn: 4.75 B 200° C. 1 h 834 29 Comparative1-1  0.77 — — A 200° C. 1 h 657 59 example 1-2  0.85 2.06 0.41 A 200° C.1 h 735 30 1-3  0.84 3.54 0.24 B 400° C. 1 h 645 45 1-4  1.17 0 — A 200°C. 1 h 663 47 1-5  2.27 9.99 0.23 — E — — — — 1-6  4.08 — — — D — — — —1-7  4.07 0.20 20.60 — E — — — —

TABLE 2 Thermal treatment Tensile Electrical Mg Sn Ni Others Crackedconditions strength conductivity No. (mass %) (mass %) Mg/Sn (mass %)Ni/Sn (mass %) edge Temperature Time (MPa) (% IACS) Invention 2-1  1.170.19 6.16 6.14 32.32 — A 200° C. 1 h 755 15 example 2-2  1.17 0.47 2.490.23 0.49 — A 200° C. 1 h 751 37 2-3  1.17 0.47 2.49 0.47 1.00 — A 200°C. 1 h 767 35 2-4  1.16 0.95 1.22 0.23 0.24 — A 200° C. 1 h 788 30 2-5 1.16 1.42 0.82 0.70 0.49 — A 200° C. 1 h 775 26 2-6  1.16 1.42 0.82 0.700.49 — A 300° C. 2 h 757 29 2-7  1.16 1.42 0.82 1.40 0.99 — B 200° C. 1h 798 24 2-8  1.16 1.42 0.82 1.40 0.99 — B 300° C. 4 h 784 27 2-9  1.162.64 0.44 3.54 1.34 — B 200° C. 1 h 861 15 2-10 1.16 4.50 0.26 0.11 0.02— B 200° C. 1 h 880 17 2-11 1.60 4.00 0.40 0.12 0.03 — B 200° C. 1 h 90117 2-12 1.76 0.96 1.83 0.71 0.74 — A 200° C. 1 h 830 26 2-13 1.76 0.961.83 0.71 0.74 — A 300° C. 4 h 862 30 2-14 1.76 0.96 1.83 1.42 1.48 — A200° C. 1 h 851 22 2-15 1.76 0.96 1.83 1.42 1.48 — A 300° C. 4 h 857 252-16 1.77 0.96 1.84 2.84 2.96 — B 200° C. 1 h 883 19 2-17 1.77 0.96 1.842.84 2.96 — B 300° C. 1 h 860 19 2-18 1.76 1.91 0.92 1.41 0.74 — A 200°C. 1 h 876 19 2-19 1.76 1.91 0.92 1.41 0.74 — A 300° C. 4 h 963 23 2-201.76 1.91 0.92 2.83 1.48 — B 200° C. 1 h 900 17 2-21 1.76 1.91 0.92 2.831.48 — B 300° C. 4 h 894 20 2-22 2.37 0.97 2.44 0.72 0.74 — A 200° C. 1h 927 22 2-23 2.37 0.97 2.44 0.72 0.74 — A 300° C. 4 h 941 27 2-24 2.370.97 2.44 1.43 1.47 — B 200° C. 1 h 929 20 2-25 2.37 0.97 2.44 1.43 1.47— B 300° C. 4 h 962 23 2-26 2.38 0.97 2.45 2.87 2.96 — B 200° C. 1 h 96417 2-27 2.38 0.97 2.45 2.87 2.96 — B 300° C. 4 h 1011 19 2-28 2.37 1.441.64 0.71 0.50 — A 200° C. 1 h 960 21 2-29 2.37 1.44 1.64 0.71 0.50 — A300° C. 4 h 984 26 2-30 2.37 1.45 1.64 1.43 0.99 — A 200° C. 1 h 980 18

TABLE 3 Mg Thermal treatment Tensile Electrical (mass Sn Ni OthersCracked conditions strength conductivity No. %) (mass %) Mg/Sn (mass %)Ni/Sn (mass %) edge Temperature Time (MPa) (% IACS) Invention 2-31 2.371.45 1.64 1.43 0.99 — A 300° C. 4 h 1001 22 example 2-32 2.37 1.93 1.232.86 1.48 — B 200° C. 1 h 963 15 2-33 2.37 1.93 1.23 2.86 1.48 — B 300°C. 4 h 996 18 2-34 3.22 0.20 16.38 0.49 2.50 — B 300° C. 2 h 934 25 2-353.64 0.20 18.43 0.49 2.48 — C 300° C. 2 h 951 26 2-36 1.76 0.96 1.830.71 0.74 P: 0.05 B 200° C. 1 h 854 23 2-37 1.76 0.96 1.83 0.71 0.74 B:0.02 B 200° C. 1 h 832 25 2-38 1.76 0.96 1.83 0.71 0.74 Fe: 0.09 B 200°C. 1 h 840 22 2-39 1.76 0.96 1.83 0.71 0.74 Co: 0.09 B 200° C. 1 h 84623 2-40 1.81 0.98 1.84 0.73 0.74 Al: 1.78 B 200° C. 1 h 909 16 2-41 1.760.96 1.83 0.71 0.74 Ag: 0.17 B 200° C. 1 h 852 26 2-42 1.76 0.96 1.830.71 0.74 Mn: 2.67 B 200° C. 1 h 878 11 2-43 1.76 0.96 1.83 0.71 0.74Zn: 4.74 B 200° C. 1 h 863 22 Comparative 2-1  0.85 2.06 0.41 0.11 0.05— A 200° C. 1 h 740 28 example 2-2  1.17 — — — — — A 200° C. 1 h 663 472-3  1.17 — — 0.47 — — A 200° C. 1 h 730 40 2-4  1.17 0.96 1.22 10.4010.83 — B 200° C. 1 h 805 9.6 2-5  1.14 5.38 0.21 0.11 0.02 — D — — — —2-6  1.80 4.98 0.36 — — — E — — — — 2-7  2.32 5.67 0.41 0.12 0.02 — E —— — — 2-8  2.27 9.99 0.23 0.11 0.01 — E — — — — 2-9  4.08 — — 0.12 — — D— — — — 2-10 4.07 0.20 20.61 0.12 0.51 — E — — — —

In Comparative example 1-1, only Mg was included, and the content of Mgwas less than 1% by mass. The tensile strength was 657 MPa which waslow.

In Comparative example 1-2, Mg and Sn were included, and the content ofMg was less than 1% by mass. The tensile strength was 735 MPa.

In Comparative example 1-3, Mg and Sn were included, the content of Mgwas less than 1% by mass, and the mass ratio Mg/Sn of the content of Mgto the content of Sn was less than 0.4. The tensile strength was 645MPa.

In Comparative example 1-4, only Mg was included, and the content of Mgwas 1% by mass or more. The tensile strength was 663 MPa which was low.

In Comparative example 1-5, Mg and Sn were included, the content of Snwas 5% by mass or more, and the mass ratio Mg/Sn of the content of Mg tothe content of Sn was less than 0.4. Cracked edges were drasticallycaused, and the copper alloy was broken during the rolling.

In Comparative example 1-6, only Mg was included, and the content of Mgwas 4% by mass or more. Large cracked edges having a length of 3 mm ormore were caused.

In Comparative example 1-7, Mg and Sn were included, and the content ofMg was 4% by mass or more. Cracked edges were drastically caused, andthe copper alloy was broken during the rolling.

In Comparative example 2-1, the content of Mg was 1.0% by mass or less.In Comparative example 2-2, Sn and Ni were not included. In Comparativeexample 2-3, Sn was not included. The tensile strengths in all ofComparative examples 2-1, 2-2, and 2-3 were less than 750 MPa.

In Comparative example 2-4, the content of Ni was 7% by mass or more,and the electrical conductivity was 9.6% IACS which was low.

In Comparative examples 2-5, 2-7, and 2-8, the contents of Sn were 5% bymass or more, and large cracked edges were caused during the coldrolling. In Comparative examples 2-7 and 2-8, the copper alloys werebroken during the rolling.

In Comparative example 2-6, Ni was not included, large cracked edgeswere caused during the cold rolling, and the copper alloy was brokenduring the rolling.

In Comparative examples 2-9 and 2-10, the contents of Mg were 4% by massor more, and large cracked edges were caused during the cold rolling. InComparative example 2-10, the copper alloy was broken during therolling.

In contrast to the above-described results, in Examples 1-1 to 1-22 andExamples 2-1 to 2-43, it was confirmed that the tensile strengths were750 MPa or more, and the electrical conductivities were 10% or more. Inaddition, no cracked edges having a size of 3 mm or more were confirmedduring the hot rolling.

From the above-described results, it was confirmed that according to thepresent invention, a copper alloy with high strength and high electricalconductivity can be produced without working troubles caused by crackededges and the like, and the copper alloy has the tensile strength of 750MPa, and the electrical conductivity of 10% or more.

INDUSTRIAL APPLICABILITY

According to the present invention, it is possible to provide a copperalloy with high strength and high electrical conductivity which requireslow raw material cost and manufacturing cost and which is excellent intensile strength, electrical conductivity, and workability. The copperalloy with high strength and high electrical conductivity can besuitably applied to electronic and electrical parts, such as connectorterminals, lead frames, and the like that are used in electronicdevices, electrical devices, and the like.

1. A copper alloy with high strength and high electrical conductivity,comprising: Mg: more than 1.0% by mass to less than 4% by mass; and Sn:more than 0.1% by mass to less than 5% by mass, with a remainderincluding Cu and inevitable impurities, wherein a mass ratio Mg/Sn of acontent of Mg to a content of Sn is in a range of 0.4 or more.
 2. Thecopper alloy with high strength and high electrical conductivityaccording to claim 1, wherein the mass ratio Mg/Sn of the content of Mgto the content of Sn is in a range of 0.8 to
 10. 3. The copper alloywith high strength and high electrical conductivity according to claim1, wherein the copper alloy further comprises at least one or moreselected from Fe, Co, Al, Ag, Mn, and Zn, and a content thereof is in arange of 0.01% by mass or more to 5% by mass or less.
 4. The copperalloy with high strength and high electrical conductivity according toclaim 1, wherein the copper alloy further comprises B: 0.001% by mass ormore to 0.5% by mass or less.
 5. The copper alloy with high strength andhigh electrical conductivity according to claim 1, wherein the copperalloy further comprises P: less than 0.004% by mass.
 6. The copper alloywith high strength and high electrical conductivity according to claim1, wherein a tensile strength is in a range of 750 MPa or more, and anelectrical conductivity is in a range of 10% IACS or more.
 7. The copperalloy with high strength and high electrical conductivity according toclaim 1, wherein the copper alloy further comprises Ni: more than 0.1%by mass to less than 7% by mass.
 8. The copper alloy with high strengthand high electrical conductivity according to claim 7, wherein a massratio Ni/Sn of a content of Ni to a content of Sn is in a range of 0.2to
 3. 9. The copper alloy with high strength and high electricalconductivity according to claim 7, wherein the copper alloy furthercomprises either one or both of P and B, and a content thereof is in arange of 0.001% by mass or more to 0.5% by mass or less.
 10. The copperalloy with high strength and high electrical conductivity according toclaim 7, wherein the copper alloy further comprises at least one or moreselected from Fe, Co, Al, Ag, Mn, and Zn, and a content thereof is in arange of 0.01% by mass or more to 5% by mass or less.
 11. The copperalloy with high strength and high electrical conductivity according toclaim 7, wherein a tensile strength is in a range of 750 MPa or more,and an electrical conductivity is in a range of 10% IACS or more.